.2 Chapter 3 Physical and Chemical Changes.. In each triad, the atomic mass of the middle element was about midway between the atomic masses of the other two elements.. Use with Chapter
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Trang 3Chapter 1 Production of Chlorofluorocarbons, 1950–1992 1
Chapter 2 Population Trends in the United States 2
Chapter 3 Physical and Chemical Changes 3
Chapter 4 Isotopes of an Element 4
Chapter 5 Quantum Numbers 5
Chapter 6 Döbereiner’s Triads 6
Chapter 7 Abundance of the Elements 7
Chapter 8 Comparing the Structures of Atoms and Ions 8
Chapter 9 Exceptions to the Octet Rule 9
Chapter 10 Balancing Chemical Equations 10
Chapter 11 Using Mole-Based Conversions 11
Chapter 12 Mole Relationships in Chemical Reactions 12
Chapter 13 Intermolecular Forces and Boiling Points 13
Chapter 14 A Simple Mercury Barometer 14
Chapter 15 Vapor Pressure Lowering 15
Chapter 16 Standard Heat of Formation 16
Chapter 17 Determining Reaction Rates 17
Chapter 18 Changing Equilibrium Concentrations in a Reaction 18
Chapter 19 Swimming Pool Chemistry 19
Chapter 20 Balancing Oxidation–Reduction Equations 20
Chapter 21 Effect of Concentration on Cell Potential 21
Chapter 22 Structural Isomers of Hexane 22
Chapter 23 Boiling Points of Organic Families 23
Chapter 24 The Chemistry of Life 24
Chapter 25 The Production of Plutonium-239 25
Chapter 26 The Phosphorus Cycle 26
Answer Key T27
Trang 5Chlorofluorocarbons (CFCs) were first produced in
the laboratory in the late 1920s They did not
become an important commercial product until some
time later Eventually, CFCs grew in popularity until
their effect on the ozone layer was discovered in the
1970s The graph shows the combined amounts of two
important CFCs produced between 1950 and 1992
Answer the following questions about the graph
1. What was the approximate amount of CFCs produced in 1950? In 1960? In 1970?
2. In what year was the largest amount of CFCs produced? About how much was produced
that year?
3. During what two-year period did the production of CFCs decrease by the greatest
amount? By about how much did their production decrease?
4. During what two-year period did the production of CFCs increase by the greatest
amount? What was the approximate percent increase during this period?
5. How confident would you feel about predicting the production levels of CFCs during the
odd numbered years 1961, 1971, and 1981? Explain
6. Could the data in the graph be presented in the form of a circle graph? Explain
Year
Amount of CFCs (billion kilograms)
0 50 100 150 200 250 300 350 400
Use with Chapter 1,
Section 1.1
Trang 61. By how much did the total U.S population increase between 1990 and 2000? What was
the percent increase during this period?
2. Calculate the total population for each of the five groups for 1990 and 2000
3. Make a bar graph that compares the population for the five groups in 1990 and 2000 In
what ways is the bar graph better than the circle graphs? In what way is it less useful?
U.S Population Distribution
(Percentages may not add up to 100% due to rounding.)
Caucasian 71.4%
Native American 0.70%
Asian American 3.8%
Hispanic American 11.8%
African American 12.2%
Caucasian 75.7%
The population of the United States is becoming more diverse The circle graphs below show the
distribution of the U.S population among five ethnic groups in 1990 and 2000 The estimated
total U.S population for those two years was 2.488 108in 1990 and 2.754 108in 2000
Trang 7Physical and chemical changes occur all around us One of the many places in which
physical and chemical changes occur is the kitchen For example, cooking spaghetti in a
pot of water on the stove involves such changes For each of the changes described below, tell
(a) whether the change that occurs is physical or chemical, and (b) how you made your choice
between these two possibilities If you are unable to decide whether the change is physical or
chemical, tell what additional information you would need in order to make a decision
1. As the water in the pot is heated, its temperature rises
2. As more heat is added, the water begins to boil and steam is produced
3. The heat used to cook is produced by burning natural gas in the stove burner
4. The metal burner on which the pot rests while being heated becomes red as its
7. When the spaghetti is cooked in the boiling water, it becomes soft
Use with Chapter 3,
Section 3.2
Trang 8Amass spectrometer is a device for separating
atoms and molecules according to their
mass A substance is first heated in a vacuum and
then ionized The ions produced are accelerated
through a magnetic field that separates ions of
dif-ferent masses The graph below was produced
when a certain element (element X) was analyzed
in a mass spectrometer Use the graph to answer
the questions below
Use with Chapter 4,
Section 4.3
1. How many isotopes of element X exist?
2. What is the mass of the most abundant isotope?
3. What is the mass of the least abundant isotope?
4. What is the mass of the heaviest isotope?
5. What is the mass of the lightest isotope?
6. Estimate the percent abundance of each isotope shown on the graph
7. Without performing any calculations, predict the approximate atomic mass for element
X Explain the basis for your prediction
8. Using the data given by the graph, calculate the weighted average atomic mass of
element X Identify the unknown element
0 5 10 15 20 25 30
196 194 192
190 198 200 202 204 206 208 210
Atomic mass (amu)
Trang 9The state of an electron in an atom can be completely described by four quantum numbers,
designated as n, , m, and ms The first, or principal, quantum number, n, indicates the
electron’s approximate distance from the nucleus The second quantum number,, describes
the shape of the electron’s orbit around the nucleus The third quantum number, m, describes
the orientation of the electron’s orbit compared to the plane of the atom The fourth quantum
number, ms, tells the direction of the electron’s spin (clockwise or counterclockwise)
The Schrödinger wave equation imposes certain mathematical restrictions on the quantum
numbers They are as follows:
n can be any integer (whole number),
can be any integer from 0 to n 1,
mcan be any integer from to , and
mscan be or
As an example, consider electrons in the first energy level of an atom, that is, n 1 In
this case, can have any integral value from 0 to (n 1), or 0 to (1 1) In other words,
must be 0 for these electrons Also, the only value that mcan have is 0 The electrons in
this energy level can have values of or for ms These restrictions agree with the
observation that the first energy level can have only two electrons Their quantum numbers
are 1, 0, 0, and 1, 0, 0
Use the rules given above to complete the table listing the quantum numbers for each
electron in a boron atom The correct quantum numbers for one electron in the atom is
Trang 10One of the first somewhat successful attempts to arrange the elements in a systematic way
was made by the German chemist Johann Wolfgang Döbereiner (1780–1849) In 1816,
Döbereiner noticed that the then accepted atomic mass of strontium (50) was midway between
the atomic masses of calcium (27.5) and barium (72.5) Note that the accepted atomic masses
for these elements today are very different from their accepted atomic masses at the time
Döbereiner made his observations Döbereiner also observed that strontium, calcium, and
bar-ium showed a gradual gradation in their properties, with the values of some of strontbar-ium’s
properties being about midway between the values of calcium and barium Döbereiner
eventu-ally found four other sets of three elements, which he called triads, that followed the same
pat-tern In each triad, the atomic mass of the middle element was about midway between the
atomic masses of the other two elements Unfortunately, because Döbereiner’s system did not
turn out to be very useful, it was largely ignored
Had Döbereiner actually discovered a way of identifying trends among the elements?
Listed below are six three-element groups in which the elements in each group are consecutive
members of the same group in the periodic table The elements in each set show a gradation in
their properties Values for the first and third element in each set are given Determine the
miss-ing value in each set by calculatmiss-ing the average of the two given values Then, compare the
val-ues you obtained with those given in the Handbook of Chemistry and Physics Record the
actual values below your calculated values Is the value of the property of the middle element
in each set midway between the values of the other two elements in the set?
Use with Chapter 6,
Trang 11Abundance of the Elements
The abundance of the elements differs significantly in various parts of the
universe The table below lists the abundance of some elements in various
parts of the universe Use the table to answer the following questions
1. What percent of all atoms in the universe are either hydrogen or helium? What percent of
all atoms in the solar system are either hydrogen or helium?
2. Explain the relatively high abundance of hydrogen and helium in the universe compared
to their relatively low abundance on Earth
3. Only the top four most abundant elements on Earth and in Earth’s crust are shown in the
table Name two additional elements you would expect to find among the top ten
ele-ments both on Earth and in Earth’s crust Explain your choices
4. Name at least three elements in addition to those shown in the table that you would
expect to find in the list of the top ten elements in the human body Explain your choices
Use with Chapter 7,
Section 7.1
Abundance (Number of atoms per 1000 atoms)*
Element Universe Solar System Earth Earth’s Crust Human Body
Trang 12Comparing the Structures of
Atoms and Ions
Comparing the Structures of
Atoms and Ions
The chemical properties of an element depend primarily on its number of valence electrons in
its atoms The noble gas elements, for example, all have similar chemical properties
because the outermost energy levels of their atoms are completely filled The chemical properties
of ions also depend on the number of valence electrons Any ion with a complete outermost
energy level will have chemical properties similar to those of the noble gas elements The
fluo-ride ion (F), for example, has a total of ten electrons, eight of which fill its outermost energy
level Fhas chemical properties, therefore, similar to those of the noble gas neon.
Shown below are the Lewis electron dot structures for five elements: sulfur (S), chlorine (Cl),
argon (Ar), potassium (K), and calcium (Ca) Answer the questions below about these structures
Use with Chapter 8,
Section 8.1
1. Write the atomic number for each of the five elements shown above
2. Write the electron configuration for each of the five elements
3. Which of the above Lewis electron dot structures is the same as the Lewis electron dot
structure for the ion S2? Explain your answer.
4. Which of the above Lewis electron dot structures is the same as that for the ion Cl?
Explain your answer
5. Which of the above Lewis electron dot structures is like that for the ion K? Explain
your answer
6. Name an ion of calcium that has chemical properties similar to those of argon Explain
your answer
Trang 13Exceptions to the Octet Rule
The octet rule is an important guide to understanding how most compounds are formed
However, there are a number of cases in which the octet rule does not apply Answer the
following questions about exceptions to the octet rule
1. Draw the Lewis structure for the compound BeF2
2. Does BeF2obey the octet rule? Explain
3. Draw the Lewis structure for the compound NO2
4. Does NO2obey the octet rule? Explain
5. Draw the Lewis structure for the compound N2F2
6. Does N2F2obey the octet rule? Explain
7. Draw the Lewis structure for the compound IF5
8. Does IF5obey the octet rule? Explain
Use with Chapter 9,
Section 9.3
Trang 14Each chemical equation below contains at least one error Identify the error or errors and
then write the correct chemical equation for the reaction
1. K(s) 2H2O(l) 0 2KOH(aq) H2(g)
2. MgCl2(aq) H2SO4(aq) 0 Mg(SO4)2(aq) 2HCl(aq)
3. AgNO3(aq) H2S(aq) 0 Ag2S(aq) HNO3(aq)
4. Sr(s) F2(g) 0 Sr2F
5. 2NaHCO3(s) 2HCl(aq) 0 2NaCl(s) 2CO2(g)
6. 2LiOH(aq) 2HBr(aq) 0 2LiBr(aq) 2H2O
7. NH4OH(aq) KOH(aq) 0 KOH(aq) NH4OH(aq)
8. 2Ca(s) Cl2(g) 0 2CaCl(aq)
9. H2SO4(aq) 2Al(NO3)3(aq) 0 Al2(SO4)3(aq) 2HNO3(aq)
Trang 15The diagram shows three containers, each of which holds a certain mass of the
substance indicated Complete the table below for each of the three substances
1. Compare and contrast the number of representative particles and the mass of UF6with
the number of representative particles and mass of CCl3CF3 Explain any differences
you observe
2. UF6is a gas used in the production of fuel for nuclear power plants How many moles of
the gas are in 100.0 g of UF6?
3. CCl3CF3is a chlorofluorocarbon responsible for the destruction of the ozone layer in
Earth’s atmosphere How many molecules of the liquid are in 1.0 g of CCl3CF3?
4. Lead (Pb) is used to make a number of different alloys What is the mass of lead present
in an alloy containing 0.15 mol of lead?
UF 6 (g) 225.0 g
CCl 3 CF 3 (l) 200.0 g
Pb (s) 250.0 g
Use with Chapter 11,
Trang 16The mole provides a convenient way of finding the amounts of the substances in a chemical
reaction The diagram below shows how this concept can be applied to the reaction
between carbon monoxide (CO) and oxygen (O2), shown in the following balanced equation
2CO(g) O2(g) 0 2CO2(g)Use the equation and the diagram to answer the following questions
Use with Chapter 12,
Section 12.2
1. What information is needed to make the types of conversions shown by double-arrow 1
in the diagram?
2. What conversion factors would be needed to make the conversions represented by
double-arrow 2 in the diagram for CO? By double-arrow 6 for CO2?
3. What information is needed to make the types of conversions represented by
double-arrows 3 and 7 in the diagram?
4. What conversion factors would be needed to make the conversions represented by
double-arrow 3 in the diagram for CO?
5. Why is it not possible to convert between the mass of a substance and the number of
representative particles, as represented by double-arrow 4 of the diagram?
6. Why is it not possible to use the mass of one substance in a chemical reaction to find the mass
of a second substance in the reaction, as represented by double-arrow 5 in the diagram?
Moles of CO
Grams of CO
3
4
6
7